Sexual size dimorphism in Tengmalm's owls Aegolius funereus outside the breeding season was investigated by trapping owls on migration during autumn. Owls were accurately sexed using PCR-based molecular techniques. Females were 4% heavier than males, but were c. 30% lighter than during the breeding season, when they carry large fat deposits and can be twice as heavy as males. Thus sexual mass dimorphism outside the breeding season was substantially lower than reported previously for the breeding season in this species. Females also had 2.5% longer wings and tail than males, but there was no difference in wing-loading, indicating that flight proficiency was similar between the sexes. Though the degree of sexual size dimorphism is small, large female size might be an adaptation for accumulating larger fat reserves, while smaller male size allows more efficient flight and hunting. This study highlights the importance of investigating sexual size dimorphism in owls outside the breeding season to avoid overestimation of female body mass.

The Hoplias malabaricus primary spermatogonium shows a large nucleus, central nucleolus, and low electron-dense cytoplasm containing nuages. In cysts, they undergo several mitotic divisions with incomplete cytokinesis, giving rise to secondary spermatogonia. These are smaller than the primary spermatogonia and their nuclei have one or two eccentric nucleoli. Spermatocytes I can be identified by the presence of synaptonemal complexes. Spermatocytes II are smaller than spermatocytes I, displaying roughly compacted chromatin. All these cell types remain interconnected by thick-walled intercellular bridges, which have membranous reinforcements during mitosis and meiosis. These cell types show a well-developed endomembranous system, one of the centrioles anchored to the plasma membrane and small nuages. Their mitochondria are large and circular, with few cristae. In the last generations of spermatogonia, the mitochondria are smaller, elongate and have more cristae. In the spermatocytes, the mitochondria are small and round. Similarities found in relation to germ cells of other teleosts are discussed.

Cricetomys gambianus is an important source of protein for human consumption in many parts of sub-Saharan Africa. Wild populations are under considerable hunting pressure, suggesting that captive rearing may be desirable. Successful captive-breeding programmes require a better understanding of reproductive physiology and behaviour. Eight groups containing a total of 68 C. gambianus females were used to characterize the reproductive pattern, including the occurrence and duration of oestrus, the cycle length, the oestrous cyclicity and the mode of ovulation. These female groups were kept in different social and physical environments and examination of vaginal smears were carried out at different periods. Results of the vaginal cytology examination showed two characteristic stages of the cycle: ‘oestrus’ and ‘anoestrus’. Oestrus appeared on average 1.3 times only in one female during 1 month, but its occurrence varied between 0.4 and two times in a month. The mean oestrous length was 3.3 days and ranged from 1.4 to 7.8 days. The average cycle length was 7.9 days but varied between 3 and 15 days. These results showed an irregular cycle pattern and revealed that C. gambianus may be an induced ovulator. Housing events, such as the presence or the absence of a male and the type of cages or rearing room, and the dry and the rainy seasons did not seem to influence the cycle pattern in this species. Further investigations on the basic reproductive biology of Cricetomys are necessary to provide the basis for developing farming methods that will yield high productivity.

In temperate ungulates, the body weight of juveniles at the onset of winter is a crucial determinant of survival and can also influence subsequent reproductive success. However, growth may be retarded post-weaning, during winter, as a result of resource restriction and/or the demands of thermoregulation in harsh climatic conditions. Post-weaning growth rates of juveniles were compared in relation to varying density in two populations of roe deer Capreolus capreolus (Chizé, Dourdan) monitored for 10 and 15 years, respectively. Body growth of fawns continued over the post-weaning stage of the juvenile period (October–March) at the rate of 0.017 kg/day at Chizé and 0.014 kg/day at Dourdan. Deer density had no influence on this post-weaning growth rate of juveniles in their first winter. However, deer born in years of high density weighed less at a given date than those born in years of low density because of their smaller body size at the onset of winter, indicating density-dependent rates of growth before weaning. At Chizé, the sexes grew at the same rate, but sexual dimorphism was apparent as males weighed about 1 kg (8%) more than females at a given date. At Dourdan, no significant sexual dimorphism was detected, although females tended to be heavier than males at a given date. We conclude that density influences juvenile body weight (through its effect on birth weight and/or post-natal growth rate) before weaning in this species and, despite continued growth after weaning, during winter, roe deer whose early growth is limited through interspecific competition cannot compensate for this early restriction.

Breeding of the threatened long-tailed bat Chalinolobus tuberculatus was studied over seven summers, 1993–2000, in temperate rainforest, Fiordland, New Zealand. Reproductive history of 789 marked bats from three social groups was investigated. Seventy per cent of births occurred over a 10-day period in mid-December. Young began flying at 5–6 weeks and nipples of reproductive females were regressing 2 weeks later. Sex ratio at birth was equal. Lactation coincided with highest annual air temperatures and peak abundance of flying invertebrates. Date of first birth varied by 4 days annually, but date of first flight varied by 17 days. Males had distended cauda epididymides at 1 year old (mean±SE = 1.63±0.16 years) and epididymal distension peaked in early autumn. Females first gave birth at 2–3 years of age (2.33±0.08 years). The short, highly synchronous breeding season, birth of single young, early mating in autumn, and late age of female sexual maturity compared to similar-sized vespertilionids, may be related to low food availability and unpredictable cold-temperate weather conditions. Annual productivity did not differ among groups but probability of survival of juveniles varied from 0.26 to 0.88 and was inversely proportional to size of natal group. Variability in breeding parameters was unrelated to climate or body condition of bats. The group with highest survival rates contained reproductive females and juveniles with significantly higher body condition. Differences in roost site or food quality within the home range of each group, varying genetic quality of members of the groups, or density-dependent mechanisms, may explain differential survival, but these hypotheses require investigation. A population crash and poor productivity in 1996 coincided with an irruption in the numbers of stoats Mustela erminea implying that predation by introduced animals can cause periodic population crashes. These results should be used to examine implications of these hypotheses on the long-term viability of Chalinolobus populations.

The dentary, a component of the transient marginal dentition found in the mandible of juveniles of the living Australian lungfish Neoceratodus forsteri, is a tooth plate exactly comparable to the tooth plates with radiating ridges that make up the marginal dentitions of Devonian dipnoans like Andreyevichthys, Orlovichthys and Ichnomylax. In N. forsteri, the dentary consists of two ridges, set almost in line with each other, and growing by the addition of cusps, of increasing sizes, to the extremity of each ridge. It is therefore equivalent to two ridges of a more normal tooth plate with radiating ridges. Despite its appearance, as a long row of sharp cusps ankylosed to a slender bone, and its position, embedded in soft tissue above the anterolabial margin of Meckel's cartilage, it is a tooth plate and is not comparable to the marginal dentitions of other vertebrates. Structure and development of the transient marginal dentition of this lungfish is another indication that dipnoans may not be the sister group of tetrapods.

The Australian sleepy lizard Tiliqua rugosa forms socially monogamous pair bonds for 6 to 8 weeks each spring before mating occurs. This behaviour could not be explained by any hypothesis involving males helping to rear their young, because pairs split up soon after mating, and males seem to have no contact with the offspring of their partners. Short monogamous associations in other lizard species are often interpreted as mate guarding by the male to assure paternity. The mate guarding hypothesis was tested by experimental separation of pairs at various times during the pairing season. Data from 73 trials indicated that males were more likely to return to females than vice versa, and that the tendency of males to return to females increased as the time of mating approached. Also, reunion was more likely in pairs that had a greater tendency to remain together during the season. These results are consistent with predictions that the monogamous relationship is a form of mate guarding by males. However, the incidence of females re-uniting with males, and the long duration of pair bonds before mating occurs are not predicted by a mate guarding hypothesis. There may be additional explanations for monogamous pairing in the sleepy lizard.

The ecology and feeding biology of two shell-burrowing polydorids associated with hermit crabs from the Philippines were investigated. Polydora umangivora and P. robi were found in shells of 15 and 28 gastropod species, respectively, occupied by nine hermit crab species. Polydora umangivora constructs U-shaped burrows in the outer shell while P. robi constructs burrows in the apex of the shell, extending to an opening along the columella of the upper body whorls. Polydora umangivora and P. robi preyed upon the embryos of three and seven species, respectively, of diogenid hermit crabs collected in the field. In laboratory feeding trials, P. robi ingested up to 230 developing eggs and 70 embryos of Calcinus gaimardii over a 6-h period. The impact of embryo predation is more apparent in hermit crab species that produce small broods of eggs (Paguristes runyanae) than in species that produce large broods of eggs (Calcinus gaimardii). Polydora robi transports the embryos to the mouth by a combination of muscular and ciliary action of the palps; ingestion follows breakage of the attachment stalk between embryo and pleopod seta. Invertebrates known and suspected to feed on host hermit crab eggs are reviewed and the evolution of polydorid/hermit crab symbioses is discussed.

A survey of freshwater snails on Mafia Island has been conducted that mapped the distribution and, by using a timed searching strategy, documented the relative levels of abundance of species. Twenty-five freshwater habitats around the island were surveyed; snails were found in 15 sites (60%). From the total number of snails collected (n=240), prosobranchs (59%) outnumbered pulmonates (41%). Potential intermediate hosts of urinary schistosomiasis were encountered and these Bulinus species were further characterized by analysis of six enzyme systems (GPI, PGM, MDH, HBDH, GDH & AcP), by inspection of DNA sequence variation within mitochondrial cytochrome oxidase sub-unit I (COI) and nuclear ribosomal internal transcribed spacer (ITS). Three species of Bulinus were found: a single B. africanus group taxon, B. nasutus, and two B. forskalii group taxa, B. forskalii and a species presently identified as Bulinus sp. in this paper. The genera Pila, Lanistes and Bulinus were widespread across the island and dominated the fauna. The remaining taxa were found in lower numbers and often only at single sites. Three prosobranchs: Lanistes purpureus, Pila ovata and Melanoides tuberculata were found. In addition to Bulinus, the pulmonates included a small discoidal planorbid (?)Ceratophallus and an ancylid (a freshwater limpet). The factors that shape the dispersal and distribution of molluscs on Mafia were considered. Water chemistry could be an important variable as both pH (mean 6.37±0.99 SD) and conductivity (mean μS=149±135 SD) were significantly different from similar habitats on neighbouring Zanzibar Island (P<0.001). The Mafian fauna is clearly associated with that of mainland Africa and Madagascar.

During the 20th century, Mediterranean landscapes underwent extensive changes. In particular, decreasing grazing pressure combined with abandonment of agricultural uplands favoured the development of Mediterranean forests with a corresponding reduction of open habitats and landscape diversity. In some parts of the Mediterranean basin, including our study area, the reduction of open landscapes took place at the same time as a rapid decline in rabbits as a result of myxomatosis. This study assesses the impact of past changes in landscape and rabbit density on the density and the breeding performance of the eagle owl Bubo bubo, one of the largest predators of Mediterranean ecosystems. Eagle owl density, nest site structure and composition at the landscape level, diet and fecundity of 35 eagle owl nesting territories was analysed for 27 years. The study area is characterized by two distinct areas, the border of the massif and the interior, in which past changes acted differently. Eagle owls in the interior were simultaneously affected by the loss of rabbits, a shift to smaller prey, and by open areas reverting to forest. All of these factors reduced the foraging efficiency of the owls. When myxomatosis decimated the rabbit population, owls in the border area switched to other mammals, birds and fish, whereas in the interior, alternative prey were less abundant. The main impacts of reduced prey availability and landscape diversity on interior pairs were: (1) lower density of breeding pairs; (2) lower diversity in landscape structure and closer habitats; (3) lower richness and diversity in the diet; (4) later egg-laying dates; (5) lower productivity.

The head bobbing of a walking bird is considered as an optokinetic response, but the question of why head bobbing is synchronized with leg movement is not clear. It is possible that head bobbing also has biomechanical correlation with leg movement at least during walking. Movement of the centre of gravity (COG) along the sagittal axis was estimated in pigeons Columba livia from carcasses and motion analysis from video films of walking. Although it was ascertained that the head thrust observed in the double support phase helps to shift the COG over the supporting foot around the beginning of the single support phase, its effect was very small. The hold phase showed correlation with the COG positioning over the supporting foot in the single support phase. Stabilization of the eyes during the single support phase may be significant for the control of balance.

Giant pandas Ailuropoda melanoleuca are a solitary, seasonally mono-oestrous species, and as such are likely to rely heavily on chemical signals to co-ordinate mating efforts. Perhaps the most crucial chemosensory task facing male pandas is the assessment of female reproductive condition on the basis of chemical cues. To test for this ability, eight male and 10 female giant pandas were presented with urine from oestrous and non-oestrous females. Males but not females displayed a significant investigatory preference for oestrous over non-oestrous female urine, as indicated by sniffing and flehmen. Males also investigated, displayed flehmen, and licked female urine more than did females. These findings indicate that female urine contains chemical cues permitting discrimination of oestrous status, and probably serves a reproductive advertisement function. The prevalence of flehmen and licking by males suggests that males may rely on the vomeronasal organ to assess female reproductive condition. Female odours may play an important role in the reproductive behaviour of male giant pandas and, therefore, may have implications for captive-breeding programmes.

Home ranges, spatial movements and patterns of habitat use were determined during a radio-tracking study on four male and six female Philippine tarsier Tarsius syrichta in Corella, Bohol, from early March to October 1999. This was the first radio-tracking study of the Philippine tarsier that included both breeding adult males and females. Home ranges averaged 6.45 ha for males and 2.45 ha for females (MCP and Kernel 95%), allowing for a density of 16 male and 41 female tarsiers per 100 ha. The habitats are primarily located in secondary lowland rainforest in early to mid succession stage, but individual tarsiers readily traversed open grass areas to move between forest patches. However, the tarsiers avoided adjacent residential areas, clearings and agricultural plantation, even if the last two were found enclosed in home-range polygons. The home range of one male overlapped extensively with that of one female and to a lesser extent with a second female. Home ranges of males showed little overlap (2.71%) and the same was observed among the females (3.35%). Nightly travel distance averaged 1636 m for males and 1119 m for females. Individuals were observed to forage and sleep solitarily. The tarsiers form groups of one adult male and one or two adult females and their offspring.

Allometric analyses of the three major salivary glands of 44 tammar wallabies Macropus eugenii and 58 parma wallabies Macropus parma from Kawau Island, New Zealand, indicate that tammar wallabies have larger parotid glands while parma wallabies have larger mandibular glands. The difference can be related to the importance of cooling in tammars, an arid-zone species, and the need for greater buffering of forestomach digesta in parma wallabies because of their greater daily food intakes and a higher browse component in their natural diet. Comparisons of sublingual gland size of these two species viewed in terms of their capacity for mucus production suggest that this may be influenced by the need to protect mucosa from mechanical and chemical injury from browse. Sample sizes of brush-tailed rock-wallabies Petrogale pencilliata and swamp wallabies Wallabia bicolor were too small for similar statistical comparisons, but they confirmed that salivary gland histology was broadly similar among all four species.

Forty leghorn chickens at the commencement of egg laying, were divided into two groups, each with 10 females and 10 males. One group was exposed to the odour of synthetic pyrazine (2-methoxy-3-isobutylpyrazine) for 16 weeks while the other acted as a control. During the first 4 weeks the hens exposed to pyrazine odour laid significantly fewer eggs (unfertilized) than the controls, but thereafter both groups laid a similar number. Mean egg mass of the pyrazine exposed hens was significantly (P = 0.012) greater (5.5%) than that of the control group. No significant difference was found in body mass or eggshell thickness. Similarly, there were no consistent significant differences between groups in oestrogen and testosterone concentrations in the blood of females and males, respectively. No pyrazine could be detected in cloacal extracts. The experiment shows that an external odour can affect the internal reproductive system of the chicken. It is suggested that the pyrazine-engendered increase in egg mass involves neuroendocrine regulation within the hypothalamus rather than hormonal interactions ‘downstream’ of the brain.

Pairing of the X and Y chromosomes during meiotic prophase and the G- and C-banding patterns were analysed in Microtus sikimensis. The karyotype of M. sikimensis from central Nepal, has 2n = 48 and FNa = 56. It has been derived from the all single-armed karyotype of M. carruthersi through a unique course of evolution. There is a synapsis between the X and Y chromosomes at pachytene and end-to-end association from diakinesis to metaphase I. Microtus sikimensis has no close karyological or morphological relationship to the other synaptic species studied so far. These data confirm that several species or lineages with synaptic condition exist in the genus Microtus, and that the ancestor of Microtus had synaptic sex chromosomes.